Problem:
While plotting an XKCD-style plot using matplotlib, you see the following error messages:
findfont: Font family 'xkcd' not found. findfont: Font family 'xkcd Script' not found. findfont: Font family 'Comic Neue' not found. findfont: Font family 'Comic Sans MS' not found.
Solution:
Install the Humor Sans font using
sudo apt -y install font-humor-sans
Additionally, you need to remove the matplotlib font cache:
rm -rf ~/.cache/matplotlib